Manageability refers to a computing platform's (“platform”) ability to enable management of the platform, which may include, for example, system diagnostics, software updates, and/or system inventory. One way to achieve manageability is to use operating system-independent processors (hereinafter “service processors”). Service processors refer to auxiliary processors on a platform that may operate independently of the operating system (“OS”).
Service processors enable out-of-band (“OOB”) manageability. OOB manageability refers to management of a platform independently of the platform's operating system. OOB management may occur regardless of the system power or OS state, and may be used to provide remote platform information, diagnostics, debugging, updating, and control capabilities, for example. OOB manageability may occur, for example, when an OS is inoperable, or when a platform is powered off, although these conditions are not necessary for OOB manageability to operate. In contrast, in-band manageability refers to management of a platform using the platform's OS. In-band manageability may occur when the OS is operational.
OOB manageability may occur using shared address mode or multiple (“multi”) address mode, such as dual address mode. In shared address mode, entities running on a platform may share a single address with the platform, such as an IP (Internet Protocol) address, where packets may be processed by an operating system. The Internet Protocol is described in the Internet Engineering Task Force (IETF) RFC 791, dated September 1981. In shared address mode, the platform may be identified by the single address such that there is no distinction between different types of traffic at the network layer. In other words, all traffic may be received at platform and processed by the operating system. Specific traffic types, such as OOB traffic (i.e., traffic to be processed by a service processor), may be identified by dedicated port numbers. In multi (e.g., dual) address mode, the service processor may have an address (e.g., IP address) unique from the platform. In this mode, the platform and another entity, such as the service processor, may be viewed as separate entities on the network by virtue of having different identities, and traffic may be distinguished using the addresses to which the packets are sent.
On the one hand, OOB traffic is better served in multi address mode because it provides a consistent network connection across all power states, OS states, and connection policies, for example. On the other hand, multi address mode may also increase network infrastructure overhead such as by duplicating the number of IP addresses that need to be supported.